1. Field of the Invention
The present invention relates to a sampler cap.
2. Discussion of the Related Art
Proper handling of a blood sample during the preanalytical phase of blood analysis is essential in order to obtain correct information on the patient's condition. During the preanalytical phase, a blood sample may coagulate, settle, react with air included in the blood sampler or exchange gas with the surroundings. All of these phenomena may bias the result of the analysis and should be avoided.
In particular for the analysis of blood gasses, any air introduced into the blood sampler and any gas exchange may bias the result of the analysis. Incorrect and misleading values may be worse for the patient than no values at all, and thus any air should be removed from the sampler and any gas exchange with the surroundings should be avoided.
Gas exchange with the surroundings may be avoided by closing the sampler. For example a syringe with a tip may be closed with a sampler cap. Such closing sampler caps are known in the prior art.
U.S. Pat. No. 5,624,402 discloses a cap for closing a syringe tip by sealing engagement with the tip of the syringe.
Air in a syringe holding a blood sample may be removed by covering the tip of the syringe by a piece of gauze, and subsequently expelling the air while holding the syringe with the tip in an upright position. This technique, however, poses a risk of the operator contacting hazardous blood samples.
Alternatively, the tip of the syringe may be provided with a sampler cap, which allows passage of air, and the sample in the syringe may be vented by means of such cap. Upon depressing the syringe plunger air may be expelled from the syringe via a venting mechanism in the cap while blood is retained by the venting mechanism. Such sampler caps are known in the prior art.
U.S. Pat. No. 5,125,415 discloses a cap in which the venting mechanism comprises a hydrophilic filter. The hydrophilic filter, e.g. a porous polypropylene impregnated with cellulose, is permeable to air under dry conditions, whereas it expands and seals the cap when exposed to blood.
The sampler caps of the prior art suffer from the disadvantage that they must be removed from the tip of the syringe prior to transfer of a test sample from the syringe to an analyzer. Accordingly, during the cap removal step as well as during the transfer step the operator is facing the risk of exposure to the blood sample.
Thus, despite the hitherto proposed sampler caps, there is still a need for a cap that needs not be removed from a sampler prior to transfer of a test sample to the analyzer.